1. Field of the Invention
The present invention relates to a recording tape cartridge rotatably accommodating a reel on which is wound a recording tape, such as a magnetic tape or the like, and to a plate spring.
2. Description of the Related Art
Conventionally, recording tape cartridges have been known in which a recording tape, such as a magnetic tape or the like, which is used as a data recording/playback medium for computers or the like, is wound on a single reel, and the reel is rotatably accommodated within a case formed of a synthetic resin. When the recording tape cartridge is in use (is loaded in a drive device), the reel of the recording tape cartridge can rotate within the case. When the recording tape cartridge is not in use (is not loaded in a drive device), the reel is locked so as to be unable to rotate within the case.
Namely, the recording tape cartridge has a braking means in order for the reel to not rotate within the case when the recording tape cartridge is not in use. For example, a structure which makes a braking member, which cannot rotate with respect to the case, engage with the reel, or the like, can be thought of as the braking means.
For example, as shown in FIG. 24, a braking member 130 is formed in the shape of a disc which is accommodated so as to be movable vertically within a reel hub 112, which is shaped as a cylindrical tube having a floor, of a reel 110. A pair of engaging projections 134, which are substantially U-shaped as seen in plan view, stand erect at the top surface of the braking member 130. A pair of rotation restricting ribs 126, which are provided so as to extend downward from the inner surface of an upper case 122, are inserted in the engaging projections 134, such that the braking member 130 cannot rotate with respect to the case 120.
The braking member 130 is usually urged toward a floor wall 114 of the reel hub 112 by an urging means such as a compression coil spring 116 or the like, and makes an annular braking gear 132, which is formed at the bottom surface of the braking member 130, mesh with an annular engaging gear 118 which is formed at the top surface of the floor wall 114 of the reel hub 112. Inadvertent rotation of the reel 110 is thereby impeded.
A substantially cylindrical operation projection 136 projects at the axially central portion of the bottom surface of the braking member 130. The operation projection 136 is inserted in a through hole 114A, which is formed in the axially central portion of the floor wall 114 of the reel hub 112, and faces a gear opening 128 formed in a substantially central portion of a lower case 124. Accordingly, when the reel 110 is to be made rotatable, the operation projection 136 (the braking member 130) is pushed upward, such that the meshing of the braking gear 132 with the engaging gear 118 is cancelled (see, for example, U.S. Pat. No. 6,452,747).
However, in such a structure, when the recording tape cartridge is not in use, the reel 110 can rise upward (movable along the axial direction of the reel 110) against the urging force of the urging means such as the compression coil spring 116 or the like. Therefore, if the user carelessly pushes the floor wall 114 of the reel hub 112 upward due to the impact of a drop or the like, as shown in FIG. 24, the braking member 130 may, in an inclined state, become anchored on the peripheral edge portion of the through hole 114A so as to tilt.
If the recording tape cartridge is loaded into a drive device in this state, not only will recording and playback not be possible, but also, breakage of the recording tape cartridge or malfunctioning of the drive device may be caused. Moreover, there is also the problem that, when the recording tape cartridge is not in use, because the reel can rotate, the recording tape may be adversely affected, such as wrinkles may form in the recording tape or the recording tape may be cut.